Variable speed drive having speed limiting means

ABSTRACT

A variable speed drive for a tractor or the like having a pulley-and-belt driving arrangement between engine and driving wheel providing adjustable variation in the speed and adjustable means for limiting the degree of variation in the speed. This is an abstract only of the specific illustration of the invention given by way of example, and is not to be used in the interpretation of the claims nor as a limitation on the scope of the invention.

United States Patent 1 Plamper [111 13,777,585 Dec. 11, 1973 VARIABLESPEED DRIVE HAVING SPEED LIMITING MEANS [75] Inventor: Gunter F.Plamper, Lakewood,

Ohio

[7 3] Assignee: MTD Products Inc., Cleveland,

Ohio

[22] Filed: Jan. 10, 1973 [21] Appl. No.: 322,500

Related US. Application Data [62] Division of Ser. No. 116,443, Feb. 18,1971, Pat. No.

[52] US. Cl 74/230.l7 D [51] Int. Cl. F16h 55/22 [58] Field of Search74/230.17 D, 242.15 R,

[56] References Cited UNlTED STATES PATENTS 3,628,390 12/1971 Van DerLely et a1 74/230.l7 D

Primary Examiner-Leonard H. Gerin Attorney-Bruce B. Krost [57] ABSTRACTA variable speed drive for a tractor or the like having apulley-and-belt driving arrangement between engine and driving wheelproviding adjustable variation in the speed and adjustable means forlimiting the degree of variation in the speed. This is an abstract onlyof the specific illustration of the invention given by way of example,and is not to be used in the interpretation of the claims nor as alimitation on the scope of the invention.

3 Claims, 6 Drawing Figures PATENTED HEB l 1 I975 SHEE 2 BF 4 PATENTEUDEC 1 1 I975 SHEE 3 IF VARIABLE SPEED DRIVE HAVING SPEED LIMITING MEANSThis application is a division of application Ser. No. 116,443, filedFeb. 18, 1971, now U.S. Pat. No. 3,583,535, issued May 30, I973.

The present invention is a variation or modification of my inventiondisclosed in my copending U.S. Pat. application Ser. No. 793,339, filedJan. 23, 1969.

An object of my invention is the provision ofa unique combination of avariable speed drive mechanism and structure for adjustably limiting therange of speed variation.

Another object is the provision for setting the maximum speed settingfora variable speed drive mechanism of the pulley-and-belt type of drive.

Another object is to provide for better control and increased safety ofa tractor or the like having a variable speed drive.

Other objects and a fuller understanding of this invention may be had byreferring to the following description and claims,taken in conjunctionwith the accompanying drawings, in which:

- FIG. 1 is a perspective view of a tractor having my invention embodiedtherein, and showing a grass cutting unit mounted on the tractor;

grass cutting unit removed for clarity of illustration);

FIG. 3 isa downwardly looking plan view of the tractor shown in FIG. 1with the upper portions thereof to better illustrate the structure andarrangement of parts embodied in my invention; 1

FIG. 4 is an enlarged detail view illustration of the parts of myinvention illustrated in FIG. 3 (but looking upwardly rather thandownwardly as in FIG. 3 and with the partsshown in different positions);

FIG. 5 is an enlarged detail view of a portion of the parts illustratedin FIG. 4, and as appearing in the preferred form of my invention; and

FIG. 6 is similar to the showing of FIG. 5, but shows the parts asappearing in a modified form of my invention.

A typical tractor to which my invention is well adaptable is the tractordenoted generally by the reference character 11, one of the uses ofwhich is the mowing of lawns. A perspective view of the tractor 11 isshown in FIG. 1 and a side view, partially in section, is shown in FIG.2. The tractor 11 has a frame 12 and extending upwardly from frame 12 isa side wall 12A enclosing the upper portions of the tractor. In thetractor illustrated there is a grass cutting unit 13 suspended frombelow the frame and which has cutting blades driven by the tractorengine. In FIG. 2 the cutting unit has been removed for purposes ofclarity in illustration.

As better seen in FIG. 2, 3 and 4, the driving mechanism includes adriving pulley 14 which is driven by the invention, and a driven pulley15 which is operatively connected to drive the rear tractor wheels. Thedriving pulley 14 has an enlarged pulley portion 16 adapted for drivingthe rotatable cutting blades of the cutting unit 13. Thereare twopulleys l7 and 19 mounted on vertical shafts which rotate the cuttingblades of the unit in the usual manner. A continuous driving belt 20 isreeved around the pulleys I6, 17 and 19 in such a man nor that uponrotation of the driving pulley, made up of pulley parts 14 and I6,pulleys l7 and 19 are simultaneously rotated to rotate the cuttingblades.

There is a variable speed sheave assembly 18 journalled on an arm 23.The stub shaft on which the sheave assembly 18 rotates is secured to thearm 23 and extends in a vertical direction from the horizontal plane ofthe arm 23. As the arm 23 is moved, the axis of the sheave assembly 18is correspondingly moved. The sheave assembly I8 is similar inconstruction and operation to the sheave assembly 18 shown and describedin my co-pending U.S. Pat. application Ser. No. 739,339, filed Jan. 23,1969.

There is a belt 21 reeved about driving pulley l4 and one of the groovesin the variable speed sheave assembly 18 whereby the driving pulley 14rotates the sheave assembly 18. There is another belt .22 reeved aboutthe driven pulley 15 and the other groove of the variable speed sheaveassembly 18, whereby rotation of the sheave assembly 18 rotates thepulley 15 and thus drives the rear tractor wheels.

The arm member 23 upon which the sh eave assembly 18 ismounted, has oneend pivotally mounted on a pivot pin 24 secured to theframe 12. Thepivot pin 24 is in a generally vertical alignment relative to thehorizontal plane of the frame 12. The arm member 23 has .a longitudinalslot 23A extending longitudinally of the arm 23 and in the end portionadjacent the pin 24. The pin 24 extends through the slot 23A whereby thearm 23 may swing in a horizontal plane about the axis of the pivot pin24. Thus the location of the axis of the sheave assembly 18 is varied bythe swinging of the arm 23.

A coil spring 25 extends longitudinally of the arm 23 and has one endanchored to the pivot pin 24 and the other end anchored to a pin in thearm 23. The biasof the spring 25 is such that it is under tension andtends to resiliently urge the arm 23 toward the pivot pin 24 at itsfixed location on the frame 12. Thus the sheave assembly 18 ,is alsoresiliently urged in a direction toward the pivot pin 24.

The position or location of the pivot pin 24 is such that the spring 25urges the sheave assembly 18 in such a direction as to maintain drivingtension on both the belts 21 and 22 at all times. Thus whether the arm23 is swung toward high-speed position or toward lowspeed position, thebelts 21 and 22 are nevertheless maintained in drivingtension by thebias of the spring In the preferred form of my invention, the pivot pin24 is so located on frame 12 thatthe arm 23 and hence the sheaveassembly 18 are not only urged in a belt tensioning direction, but alsoin a direction as to urge the sheave assembly 18 toward a high-speedposition. Thus, the spring 25 performs a dual function of not onlymaintaining driving tension on the belts 21 and 22 but also ofresiliently urging the sheave assembly 18 toward its high-speed positionand away from its lowspeed position. For obtaining this purpose, thepivot pin 24 is located somewhat more toward the rear of the tractor(more toward the left in FIG. 3) than it would be located if it merelyperformed the function of maintaining driving tension on belts 21 and22. The difference in the two locations need not be great and it isdetermined by how much resilient urging is desired for biasing themechanism toward high-speed operation. In view of the dual function ofthe spring 25, it may be said that in this preferred arrangement thatthere is included resilient biasing means for maintaining the belts 21and 22 in belt tensioning condition and also resilient biasing means forurging the sheave assembly I8 toward one of its speed positions, whichspeed position preferably would be its high-speed position.

The slot 23A permits the arm 23 to move longitudinally under the tensionof the spring 25 relative to the pivot pin 24 inserted in the elongatedslot 23A.

Connected to the free end of the arm 23 is a connecting rod 27 which isprovided for manually swinging the free end of arm 23 forwardly orrearwardly as desired. An actuating foot pedal 28 is pivotally carriedon pivot 31 secured to the frame 12. The pedal 28 is connected throughconnection 33 to rod 27.

Thus the operators foot by pressing the foot pedal 28 will move thepedal towards low-speed position and by permitting the foot pedal 28 topivotally swing backward towards the rear of the tractor will permit thepedal to move toward high-speed position, toward which it is resilientlyurged.

The actuating pedal 28 is operatively connected through a hinge linkage30, 38 and 30A to a hand actuating lever 29 in such manner that thepedal 28 and lever 29 move simultaneously. When the pedal 28 isdepressed towards low-speed position the upper handle end of lever 29will simultaneously move backwardly and upwardly toward its low-speedposition. Thus the mechanism is actuatable between high-speed andlowspeed positions, and in positions therebetween, by either or both ofthe pedal 28 and lever 29. The lever 29 is pivotally carried on thepivot pin 32 secured to the side wall 12A of the tractor frame. Aconnecting mechanism 33 so interconnects the pedal 28 and lever 29 suchthat movement of the pedal 28 and lever 29 correspondingly moves theconnecting rod 27 and thus to swing the arm 23 between its high andlow-speed positions.

In FIG. 4, the low-speed position of connecting rod 27, arm 23, sheaveassembly 18, and belts 21 and 22 is shown in full lines. Contrariwise,the high-speed position of connecting rod 27, arm 23, sheave assembly18, and belts 21 and 22 is shown in broken lines.

In view of the fact that in this preferred form of my invention themechanism is resiliently urged toward high-speed position, it may benoted that in the absence of some limitation or stop means, that thetractor would tend to immediately and always go to its high-speedoperation. In the operation of a tractor, such as a tractor used formowing grass on slopes and the like or under different drivingconditions, it is desired to provide in many circumstances a maximumhigh-speed for the device. This is done by having an adjustable limitingmeans which stops movement of the actuating parts beyond a pre-selectedposition. In the preferred form of my invention, and in particular shownin FIGS. 1 and 2, there is provided a limiting finger member 34pivotally carried by the frame 12 on a pivot pin 35 whereby the upperend of the finger member 34 may be pivotally swung forwardly andrearwardly. This finger member 34 is positioned inboard of the side wall12A of the tractor and closely adjacent to the side wall. There is aslot 37 at a location above the pivot pin 35 through which the upper endof the finger member 34 protrudes. The upper free end of the fingermember 34 is a bentover upper end portion 34A which extends outwardlyfrom the side wall 12A in a position to be manually grasped by theoperator and thus to swing the finger member 34 forwardly and rearwardlyas desired. Close to and below the upper end portion 34A there is adetent portion 348 integrally carried by the finger member 34. Thisdetent portion 343 is formed by bending a side edge portion of thefinger member 34 at right angles to the plane of the finger member 34.This detent portion 348 is directed outwardly of the tractor housing andthus toward the side wall 12A.

A side wall 12A of the tractor has a plurality of slits 12B arranged inan are about the axis of the pivot pin 35. These slits 12B being spacedapart. In the illustration shown there are four slits 12B arranged insuch an arc. The size of each slit 12B is such that the detent portion34B of the finger member 34 may extend into and through a respectiveslit 128.

The mounting of the finger member 34 and its construction is such thatthe upper end portion 34A is resiliently biased outwardly of the tractorand thus to urge the detent portion 348 outwardly through one of theslits 12B when aligned therewith. Thus the operator sitting on thetractor 11, by seizing the bentover portion 34A and pressing it inwardlyof the tractor, may disengage the detent portion 34B from a slit 12B andthus move the finger member 34 to any of selected of the four alternatepositions provided by the four slits 12B. The finger member 34 may thusbe permitted to move under its bias so as to insert its detent portion348 into the selected one of the four slits 12B.

Inasmuch as the bent over end portion 34A is in the arcuate path of thelever 29, it is seen that the position of the finger member 34determines how far forwardly and downwardly the lever 29 may swing. Aslever 29 and pedal 28 are operatively interconnected, the position ofthe finger member 34 also determines how far rearwardly and upwardly thepedal 28 may be depressed.

There is thus provided a practical and economical arrangement forproviding a limiting stop so as to set the upper limit to which thedriving mechanism may go towards high-speed operation. The operator ofthe tractor may thus determine the range of permissible movement of theactuating mechanism and thus provide for the maximum range of speed. Bysetting the finger member to selected position, the maximum speed towhich the tractor will go may be predetermined.

In FIG. 5 the reference character X indicates the location of the axisof the pivot pin 24 in the preferred form of the invention, such asshown in FIGS. 1 to 5 inclusive. In FIG. 5, the distance between X to Zrepresents the differnece in the length of the spring 25 between highand low speeds when the parts are in the preferred form of said FIGS. 1to 5 inclusive. The reference character Y illustrates the location ofthe axis of the pivot pin 24 if it were located so that only maintenanceof driving tension is maintained on belts 21 and 22 but not so as tourge the mechanism toward either high or low speed position. This pointY might be referred to as a neutral position insofar as the spring 25urging the arm 23 in a direction to maintain driving tension on belts 21and 22.

In FIG. 6 there is illustrated a modified form of my invention. In thismodified form of the invention, a pivot pin, now denoted by thereference character 24A, is located at the neutral position Y. When inthis position, the spring 25 only biases the sheave assembly 18 in adirection to maintain driving tension in belts 21 and 22. Thus, in thismodified form, the spring 25 performs only this single function asdescribed. In this modified form illustrated in FIG. 6, there isprovided a helper spring 25A which provides the other resilient biasingfunction. One end of the helper spring 25A is anchored to the arm 23 andthe other end is anchored by an anchor pin 36 to the frame 12. Thetension on helper spring 25A is such as to resiliently urge the arm 23to the left in FIG. 6 and thus to urge the arm 23 to swing towardhigh-speed position. Thus in FIG. 6, two springs are utilized forobtaining the dual biasing function whereas in the preferred form ofFIGS. 1 to 5 inclusive, one spring 25 is utilized. in both cases thedriving mechanism is'urged toward its high-speed position and in bothmodifications a limiting means for limiting the maximum movement of theactuating mechanism towards high-speed position, such as previouslydescribed, is utilized.

In the use of a tractor utilizing my invention, the operator of thetractor may determine the maximum speed (obtainable with the particulartractor) at which he wishes to proceed under the situation andconditions then in existence. He sets this desired maximum speed bypre-setting the position of the finger member 34 to one of its pluralalternate positions by manually moving the portion 34A to a desiredlocation where detent portion 348 engages in a slit 12B at thatlocation.

During the travel of the tractor, if the operator does not manually moveor otherwise control either the pedal 28 or the lever 29, then theresilient bias on the parts in such that the pedal 28 will swingupwardly and rearwardly toward its high-speed position, and the upperend of lever 29 will swing forwardly and downwardly toward itshigh-speed position, both to the limit determined by the pre-setting ofthe finger member 34 to selected position. Upon the operator desiring tocause the tractor to travel at a lower rate of speed, he may press downand forwardly on the pedal 28 to depress the same to obtain the lowerspeed desired, or to a completely depressed position to stop the drivingof the tractor. Similarly, to cause the tractor to travel at a lowerrate of speed the operator may swing the upper end of the lever 29rearwardly and upwardly to obtain the lower speed desired, or to acompletely rearward position to stop the driving of the tractor. As bothpedal 28 and lever 29 move in unison, the operator may thus readilycontrol the speed of the tractor by manipulating either pedal 28 orlever 29, or by simultaneously manipulating both pedal 28 and lever 29.

The present disclosure includes that contained in the appended claims,as well as that of the foregoing description.

Although this invention has been described in its preferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form has been made only by way of exampleand that numerous changes in the details of construction and thecombination and arrangement of parts may be re sorted to withoutdeparting from the spirit and the scope of the invention as hereinafterclaimed.

What is claimed is:

1. In a driving mechanism for a tractor having a frame, the mechanismhaving a variable-pitch sheave assembly operatively connected by beltsto a driving pulley and a driven pulley for changing the speed ratio ofsaid pulleys between to obtain a high-speed rate and a low-speed rate ofthe driven pulley upon swinging of said sheave assembly between alow-speed position and a high-speed position to vary the spacing of theaxis of the sheave assembly relative to the axes of said pulleys,resiliently yieldable belt-tensioning means for urging said sheaveassembly in a direction for maintaining the driving tension on saidbelts during movement of the sheave assembly between low-speed andhigh-speed positions, said belt-tensioning means exerting a firstcomponent of force tending to urge said sheave assembly away fromhigh-speed position in maintaining the tension on said belts, theimprovement of resilient biasing means anchored to said frame andoperatively connected to said sheave assembly, said resilient biasingmeans being anchored to said frame and disposed to exert a secondcomponent of force tending to urge said sheave assembly towardhigh-speed position, said second component of force being substantiallygreater than said first component of force whereby the said sheaveassembly is resiliently urged toward high-speed position, and adjustablelimiting means carried by the frame and selectively adjustable to aplurality of limit positions to limit the maximum extent of the range ofmovement of the sheave assembly toward high-speed position and thuslimiting the maximum speed of the driven pulley.

2. The improvement as claimed in claim 1 and in which saidbelt-tensioning means and said resilient biasing means are combined in asingle resilient means.

3. The improvement as claimed in claim 1 and in which thebelt-tensioning means is a first spring extended in a line generallycoinciding with the line of said first component of force and saidresilient biasing means is a second spring extended in a line generallycoinciding with the line of said second component of force.

v UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 3,777,585 DatedDecember 11, 1973 7 Patent No.

' Gunter F. Plamper Inventor(s) 'It is certified that error appears inthe above identified patent and that said' Letters Patent are herebycorrected as shown below:

On the cover sheet item "[62] Pat. No. 3,583,535" should read 3,759,342Column 1, line 3, "3,583,535 issued rlMay 30, 1973'5shou1d read3,759,342 issuedl september 18,

Signederld seaied-thisflrd day of December 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. 0, MARSHALL DANN Attesting Officer I Commissioner ofPatents 7 usc oMm-oc scan-pea U. S GOVERNMENT PRINTING OFFICE Ii! O-3$'-J34.

FORM PO-1050 (10-69)

1. In a driving mechanism for a tractor having a frame, the mechanismhaving a variable-pitch sheave assembly operatively connected by beltsto a driving pulley and a driven pulley for changing the speed ratio ofsaid pulleys between to obtain a high-speed rate and a low-speed rate ofthe driven pulley upon swinging of said sheave assembly between alow-speed position and a high-speed position to vary the spacing of theaxis of the sheave assembly relative to the axes of said pulleys,resiliently yieldable belt-tensioning means for urging said sheaveassembly in a direction for maintaining the driving tension on saidbelts during movement of the sheave assembly between low-speed andhigh-speed positions, said belt-tensioning means exerting a firstcomponent of force tending to urge said sheave assembly away fromhigh-speed position in maintaining the tension on said belts, theimprovement of resilient biasing means anchored to said frame andoperatively connected to said sheave assembly, said resilient biasingmeans being anchored to said frame and disposed to exert a secondcomponent of force tending to urge said sheave assembly towardhigh-speed position, said second component of force being substantiallygreater than said first component of force whereby the said sheaveassembly is resiliently urged toward high-speed position, and adjustablelimiting means carried by the frame and selectively adjustable to aplurality of limit positions to limit the maximum extent of the range ofmovement of the sheave assembly toward high-speed position and thuslimiting the maximum speed of the driven pulley.
 2. The improvement asclaimed in claim 1 and in which said belt-tensioning means and saidresilient biasing means are combined in a single resilient means.
 3. Theimprovement as claimed in claim 1 and in which the belt-tensioning meansis a first spring extended in a line generally coinciding with the lineof said first component of force and said resilient biasing means is asecond spring extended in a line generally coinciding with the line ofsaid second component of force.